1. Field of the Invention
The present invention relates to a printing press having rotatably mounted cylinders. At least two adjacent cylinders roll on one another through bearer rings (Schmitz rings). The present invention also relates to a method of controlling a printing press.
In rotary printing presses it is known for adjacent cylinders in a printing unit to have bearer rings firmly connected to a cylinder, in order to avoid effects of channel impacts, which impair the printing quality. Blanket and plate cylinders rolling on one another have bearer rings at the sides for that purpose, which are pressed against one another during printing operation and thus roll on one another. That prevents the pressure from being increased as the channel in the blanket cylinder or plate cylinder passes through and prevents what are known as channel impacts from occurring, which lead to oscillations and therefore to a worsening of the printing quality. In addition, German Patent DE 195 01 243 C5 discloses the use of bearer rings which are not firmly connected to the associated cylinder. For that purpose, the cylinder of a rotary printing press has journals on which a rotatable bearer ring is mounted. In that way, it is not possible for any undesired transmission of torques to arise through bearer rings connected to one another by a force-locking connection. The intention is to prevent influences on the printed image as a result of avoiding the transmission of a torque. However, there are situations during printing operation in which such an influence on the printed image is desired. Such an influence, however, is possible neither in the case of a firmly mounted bearer ring nor in the case of a rotatably mounted bearer ring through which no torque can be transmitted.